Experimentation Circle
by Hive Mentality
Summary: Mummy and Daddy experimented on each other, on Mycroft and Sherlock, and now that Sherlock has experimented on John, it's his turn to experiment back. So why is it taking him so long? Isn't that what families did? Light S/J and Young!Sherlock.


**Experimentation Circle**

Sherlock was not dense by any stretch of the imagination, but he would be the first to admit, albeit grudgingly, that there were some things that simply eluded him.

He'd thought he'd had this figured out (after all, experimenting on each other was what families did, wasn't it?) but now he was more confused than ever.

Sherlock and John had been in this…whatever this was that they had… for nearly a month now. They'd toggled between colleagues to friends to more for a long time before they'd settled into something that just _worked_. They hadn't put a name on it and they didn't really want to, and to Sherlock it was becoming increasingly apparent that John wouldn't be leaving him any time soon.

They fell into a comfortable pattern of tea—murder—movie night—assassination attempt—dinner and the cinema—bank robbery—grocery shopping; and for a while things seemed absolutely perfect.

But for all that Sherlock had tried, John seemed utterly uninterested in participating in any of Sherlock's experiments, let alone conducting any of his own.

He'd tried to remain realistic about it—after all, John was strong willed and stubborn and so glaringly _kind_ that he'd have informed Sherlock of a problem in their relationship long ago if he had one. Sherlock knew this.

Still… the materials next to John's desk that he'd strategically selected to be _perfectly_ relevant to any medical-field related experiment John wanted remained untouched, and for all that Sherlock called himself a detective, he couldn't figure out why.

Why didn't John want to experiment on him? Isn't that just what family did?

Sherlock had been actively participating in experiments since he was five years old. He'd come into the kitchen one day to find Mummy carefully measuring something into a teapot. Her face lit up when she saw him, and she beckoned him over. Scooping him up in her arms so he could peer in through the top of the pot at the green powder inside, she explained what she was up to—something about the potency of a particular Eastern supplement that was too complex even for a five year old like Sherlock to grasp. He found it exciting none the less, and she'd delightedly handed him a cuppa with the express instructions to deliver it to Daddy ("and none for Mycroft dear, the dosages are all wrong for that").

Of course, Mycroft had been the first to try the tea, and he'd complained about the bitter taste only until it began to take effect. After several hours of loopy ramblings and a near constant stream of data Sherlock was happy not only to report that the supplements really were quite potent (much to Mummy's chagrin, though she was satisfied with the results none the less), but also that his next experiment was well underway.

As John passed by the chemicals he'd stored in the dark cupboard in favor of making himself some tea, Sherlock's niggling doubt reminded him that perhaps John…well, some people just didn't understand experimenting.

When Sherlock was eight years old a minor (yet very informative) reaction between two chemicals had forced Sherlock outside for the day while his room (and Mycroft's—a necessary sacrifice in the name of science) was able to air out, windows flung wide with an occasional wisp of smoke still escaping.

Sherlock had spent the better half of the morning scouring the lawn for insect specimens while Mycroft alternated between reading and watching him from the porch.

They lived in a fairly secluded neighborhood and Mummy gave him permission to go as far as the park on the corner, so when he suddenly realized that secluding his sample to his own yard may bias his results for future experiments, he'd picked up his jar and his magnifying glass and slipped off before Mycroft could notice him go.

He'd seen a few other children playing at the park before, but they were a few years older than he was (there weren't many children his age in the neighborhood, anyway). Mycroft didn't seem to like them, and that was as good a reason as any for him to play on his own.

Either way, they weren't there when he arrived, and he had some samples to find.

There were a plethora of species to choose from in the park, and it didn't take him long to fill the jar. He'd settled down to dig around the base of a tree, so focused with his search that he didn't notice someone join him until the shadow flicked over the grass next to him. He turned around expecting Mycroft, thoroughly prepared to stick his tongue out at him and tell him to go find somewhere else to read.

It wasn't Mycroft. Though Sherlock knew he'd seen the boy before, he had never spoken to him. The boy was leaning over Sherlock to watch him.

"…What are you doing?" He asked, his face screwed up in mild disgust at the writhing jar. Sherlock cocked his head to the side. Wasn't it obvious?

"I'm collecting specimens for an experiment." He responded, holding the jar up so that the boy could see it better, "The variety of species in the park isn't exactly ideal, but Mummy says I'm not supposed to go further, so…" he trailed off, at the look the boy was giving him, deciding that perhaps he'd said something wrong.

"What are you _talking_ about?" He asked grabbing the jar from him, "That's stupid. Let me see."

"Hey! Give that back!" Sherlock shouted, and the boy scoffed, raising it above his head.

"Make me!" He said. Sherlock jumped up, trying to grab it from him, but he was short for his age and younger besides, and he could hardly reach his raised arm past the boy's elbow.

"You'll—ruin—my—sample!" Sherlock grit out, trying to pull his arm down.

"They're just bugs, stupid!" The boy said, pushing Sherlock off him. He took a step back, and his foot caught on a tree root. The jar slipped from him hand as he tried to catch his balance, and Sherlock watched in horror as it fell to the ground and broke.

Sherlock knew it was a bad idea to pick a fight with someone bigger than you—he'd learned that from Mycroft—but he did it anyway. Sherlock jumped up and tackled the boy, who cried out in surprise. They rolled around in the dirt, all limbs and elbows, as Sherlock tried his best to avoid the spot where his samples were now crawling around on the ground together.

The boy flipped up on top of him, and when he saw him pull his fist back he knew exactly where this was going. He screwed his eyes shut and brought his arms up to protect his face.

And then just as quickly the boy was hauled off him by the collar, and Sherlock braved a peek to see what was happening. Mycroft was staring at the boy coldly, and his knuckles were white where they gripped his shirt. The boy was suddenly much less brave—Mycroft was a good head taller than he was, glaring at him intently, and now it was two on one—and Mycroft said nothing even as he jerked out of his grip and backed off, deciding it was best to retreat.

"Freak!" He shouted at Sherlock, turning to run as he did. Mycroft's hand twitched at that, but otherwise he didn't move until the boy was completely gone. Then he turned his attention to Sherlock, who was trying in vain to find the insects that had escaped. He picked up the broken jar and looked Mycroft, his expression carefully blank despite the dirt and forming bruises.

"All right, Sherlock?" He asked, and Sherlock looked past him at where Mycroft had dropped his book several yards away. Sherlock looked back to him, noting that he was breathing rather quicker than normal. Sherlock gave him a tight nod.

"My samples have all crawled off…" He said, eyeing the jar somewhat sadly. Mycroft gave him an understanding smile and helped him to his feet.

"I'll help you find some more tomorrow, hmm?" He said, "Until then, Daddy's starting on his experiment, he wanted me to fetch you." Sherlock perked up at that. Daddy's experiments were always entertaining.

Being a psychologist, he tended toward the more social experiments which Sherlock especially enjoyed. This particular experiment they'd been planning for some time. Daddy had acquired for himself 5ccs of Tetrodotoxin infused in tobacco, a drug which would put him into a deathlike state. Completely harmless, he'd assured, but very convincing. He'd elicited Sherlock's help to study and record Mummy's and Mycroft's reaction in order to better understand the nuances of grief.

It really was exciting, and it made him feel a little better. Sherlock sniffed and wiped some of the dirt from his face onto his sleeve. Mycroft helped carefully pick up the pieces of the broken jar.

"…He said my experiment was stupid." Sherlock said, and Mycroft gave his hand a light squeeze.

"Don't mind him. Some people just don't understand." Mycroft said, "Now come along, Daddy's waiting."

Sherlock stumbled inside and shirked his coat off on the floor with shaky movements. He sat heavily on the sofa, still pressing his balled up scarf to the gash on his forehead. The amount of blood was a bit worrying, but he remembered John mentioning that head wounds bled a lot. His scarf was ruined, though.

"Sherlock, is that you?" John called from the kitchen. It would have struck him as a funny question—of course it was him, who else would it be—but he didn't really want to concentrate on that right now. Sherlock could hear his blood pumping in his ears, and his head was throbbing. He could also hear the water running in the kitchen, meaning John was starting the kettle, and John turned the tap off as he called again and made his way over: "Sherlock, where the hell have you—Oh my god, what happened?"

John was suddenly right in front of him, one hand on the nape of his neck and the other gingerly lifting the scarf, "Let me see." Sherlock did what he was told, and John clucked his tongue as he inspected the cut.

"Call the Yard… Tell 'em they've got themselves the wrong murderer." Sherlock said. John gave him a pointed look but decided to let it slide. He gently wiped the blood from Sherlock's face, turning his head to the side slightly.

"Lestrade can wait." John stood and left the room, assuring him he'd be right back. Sherlock leaned back and closed his eyes for a moment, opening them again when John gave his shoulder a light shake.

"No sleeping, Sherlock." He said, and Sherlock blinked before nodding slowly. "Can you tell me what happened while I test your pupil dilation?"

"I already told you that Lestrade's suspect was obviously not the killer—wait, say again." Sherlock said urgently, leaning forward and ignoring the increased ringing in his ears.

"I need to test your pupil dilation, Sherlock, pay attention." John chided him. _Test, _John had said. Sherlock grinned. Of course. Why didn't he see this before?

"John, what is my normal blood pressure?" Sherlock asked. John gave in a confused look but answered without hesitation none the less while shining the light in both of his eyes in turn. He hummed, satisfied with what he saw, and took to cleaning out the cut on Sherlock's forehead.

"Around 116/68… What does that have to do with anything?" John asked, mildly concerned by the random topic change. Sherlock smiled slightly at the answer. He mentally berated himself for being so foolish. Of course, John was a medical professional. He would never experiment on Sherlock in the same way Sherlock did on him, and because of this Sherlock had almost missed it.

"Never mind, John." Sherlock said. "In any case, I was following up on a lead and that lead did not want to be followed." He summed up the incident quickly.

"Well, you don't seem to have a concussion, but I'd like to keep an eye on you anyway. Doesn't look like you'll be needing stitches, at least." John said, taping a piece of gauze over the cut, "You can be a real idiot sometimes, you know." He added, more fondly than anything else.

"I know." Sherlock said. And he could be—because as long as John had known him he'd been experimenting on him: average blood pressure, body temperature, respirations, blood type, his body's responses to different medications…

He really was an idiot sometimes.


End file.
